Method of making heat exchangers



May 9 1933. w. A. JONES ET AL METHOD OF MAKING HEAT EXCHANGERS 3Sheets-Sheet 1 Filed Sept. 18, 1930 m} Q g nes 3% INVENTQRQQ -19 JohnPre e THEIR A QRNEY May 9, 1933. w A, JONES ET AL 1,908,363

' METHOD OF MAKING HEAT EXCHANGERS Filed Sept. 18, 1930 3 Sheets-SheetTHElR AT OR EY y 1933- w. A. JONES ET AL 1,908,363

METHOD OF MAKING HEAT EXCHANGERS Filed Sept. 18, 1930 5 SheetS-Sheet I5I VENTOR W09. Jones 7101/ Preniiae THEIRAT ORN Y Patented May 9, 1933UNITED STATES PATENT OFFICE WILLIAM A. JONES, OF WEST NEW BRIGHTON, NEWYORK, AND JOHN PRENTIGE, OF BAYONNE, NEW JERSEY, ASSIGNORS TO THEBABCOCK 8a WILGOX COMPANY, OF BAYONNE, NEW JERSEY, A CORPORATION OF NEWJERSEY METHOD OF MAKING HEAT EXCHANGERS Application filed September 18,1930. Serial No. 482,669.

In treating hydrocarbon oils the use of mercury vapor, or other highlyheated vapor, as a heat transfer fluid introduces a dliferential intemperature between the parts carrying the respective fluids, thatrenders it difficult to build heat exchangers capable of withstandingthe stresses set up by the temperature difference without producmg leakswhich cause serious direct loss of the mercury, or losses due tointermingling of the mercury and oil.

This invention therefore relates to a mercury or other vapor heatexchanger including tubular members, each of which is so assembled thatan uncommon degree of stress elongation may take place without producingleakage of the component elements, and in which highly eflicient heattransfer is accomplished by an arrangement of tubes, one within another,which permits the formation of an enveloping film of mercury vapor in ajacket around the body of heat receiving oil and co-extensive therewith,and separated therefrom by a thin metal wall acting as a heat transfermedium.

To accomplish this result each tubular loop member includes an outertube jacket and an inner tube annularly spaced throughout their length,and the tubeshave different radii at their bends whereby increasedclearance is provided at the loop permitting longitudinal expansion ofthe one with respect to the other, the return bend of each loop alsohaving a radius sufficient to permit removal of deposits therein by theusual turbining methods now in practice, all joints between tubes beingwelded to prevent leakage of mercury or other vapor.

To connect the inner tubes of the tubular loop members in series returnbend fittings are provided each of which is so formed that, in additionto a passage directing the fluid flow at 180 degrees, there are alsopassages forming continuations of the inner tubes of connected loops,said continuation passages being closedby removable plugs which permitcleaning of the inner tubes by simply removing caps and workingtherethrough with the usual turbinin equipment, and thus avoiding thenecesslty of making a disconnecting joint between the tubes and fittingswith the consequent grief encountered in maintaining such joints free ofleakage where high temperatures and pressures prevail.

In the drawings which illustrate a practical form which the inventionmay assume- Fig. 1 is a top plan view of an exchanger with the enclosingcasing cut away in a transverse plane to show the arrangement of tubularmembers;

Fig. 2 is a side elevation with the enclosing casing cutjthrough in avertical plane to expose the tubular loop elements;

Fig. 3 is an end .elevation with the casing cut through in a verticalplane to show the arrangement of tubular loop members;

Fig. 4 is an end elevation similar to that shown in Fig. 3 but of theopposite end, thereby showing the arrangement of the return bendfittings whereby the inner tubes are connected in series;

Fig. 5 is a side elevation partly in section lllustrating theconstruction of the return bend fittings used to interconnect the innertubes of the tubular loop members;

Fig. 6 is an end elevation of assembled halves of the return bend whichultimately forms an integral part of each tubular loop member;

Fig. 7 is a plan view showing the interior of the lower half of thereturn bend illustrated in Fig. 6;

Fig. 8 is a sectional view of one return bend ita longL the verticalplane 88 indicated in Fig. 9 is a fragmentary end view of Fig. 5.

The invention, as "illustrated in the drawings, includes a bank oftubular loop members 1 each of identical construction, as will behereinafter set forth, the banks being divided into groups lettered A, Band C. Each group comprises a number of these horizontal tubular loopmembers 1 in piled relation, one overlying the other.

Each tubular loop member includes an inner tube 2 bent at 180 degrees toform a return loop having the legs 3 and 4, and surrounding Which is anenveloping jacket tube 5 of larger diameter than the tube 2 and thusspaced from the outside of tube 2 throughout its length so as to form.the annular passage 6 between the two tubes.

Due to the length of the component tubes 2 and of the tubular loopmembers, and the high temperature and pressure at which the exchanger,of which they are a part, is operated, the ability to take care ofexpansive elongation of the one with respect to the other, becomes ofprime importance; with the outer or enveloping jacket tube 5 at atemperature of approximately 900 degrees Fahr., and the inner tube at amuch lower temperature, considerable elongation of the outer tube 5,with respect to the inner tube 2, will take place; this is taken care ofby making the return bend of the outer or jacket tube with a radiusproviding sufiicient clearance as shown so that both expansion andcontraction are taken care of without imposing any undue stress upon thetubes and welds, or, in other words, the tubular loop member isselfprotecting in regard to expansion and contraction.

The return bend of the outer jacket tube 5 is made up by combining twopressed steel halves 7 and 8 diametrically increased in cross sectionintermediate the extremities which, when assembled, fit in closelyabutting relation and are joined by welding along the seams 9. Theextremities of this bend are of the same cross section as the envelopingtubular member 5 as indicated at 10, and when the assembled return bendis placed in position the parallel legs of the enveloping tubular member5 are in closely abutting relation with the ends 10 of the return bendand are welded thereto as at 11, thereby providing a looped envelopingtube with an enlarged return bend affording clearance. The lower half ofthe return bend has supporting ribs 12 and 13 which carry the returnbend of the inner tube 2 and permit a sliding action between the tubes 2and 5 when elongation takes lace. p In assembling the tubular members 2and 5 the inner tubular member 2 has its legs 3 and 4 slipped into theenveloping tubes 14 and 15 which, together with the return bend built upas previously described are to form the completed enveloping tube 5. Theends of the completedtube are welded as at 16 and 17 to the outersurface of the inner tube legs 3 and 4, respectively, the two tube loopsbeing so placed with respect to each other'that their normal relation,in a cooled condition, is as indicated in Figs. 1, 2 and 8 with theouter side of the return bend of the inner tube 2 lying substantiallyagainst the inner wall of the return bend of the enveloping tube 5 andwith the-lower side of the inner tube 2 resting upon the ribs 12 and 13;thus, as the enveloping tube 5 lengthens out the enlarged space formedby the welded return bend halves 7 and 8 afl'ords clearance for theelongation of the enveloping tube 5 with respect to the inner tube 2and, at operating temperatures, positions the inner tube 2 approximatelycentrally with respect to the cross section of the enveloping tubes 5throughout the entire length of the two tubes, thus providing a uniformpassage between the tubes at all points.

The return bend fitting which is used to interconnect the looped tubes 2has duplicated heads 18 and 19 joined together in an integral casting bymetal forming a passage 20 directed at 180 degrees, but with the inletand outlet thereof extended axially to form continuations of the tubepassages as indicated at 21. Each passage 21 has a tapered seat 22 atits outer end against which a closure plug 23 is clamped, said plug alsohaving a tapered face cooperating with the seat 22 to form apressure-tight joint. This plug 23 is secured in place by an undercutgroove 24 which produces an overhanging lip 25 under which rests theledge 26 of a two-part clamping member said lip 25 being cut away for aportion of its periphery to permit the placing and removing of theclamping member. This two-part clamping member has a circular nut 27carrying the ledge 26 and is threaded as at 28 to receive a jackingscrew 29, the end 30 of which abutts the plug 23 and holds the latter inplace. The entrance ends 31 and 32 of the return bend fitting areprovided, exteriorly, .1 with lugs 33 for limiting the proximity oftubular members. These ends 31 and 32 are counterbored as at 34 and arefurther provided with circumferential grooves 35 so that the ends of theinner tubes 2 of the loop members 100 may be expanded to a fluid-tightfit against the walls of the entrance passages of the re- .turn bendfittings.-

It will be obvious that by removing the plugs 23 the tubes 2 may becleaned by the usual turbining methods, the radius of the bend at theopposite end of the tube being suflicient to permit of this.

With reference to Figs. 3 and 4, it will be seen that return bendfittings of the type illustrated in Fig. 5, and just described, are usedto interconnect the inner tubes 2 in series and to connect the groups A,B and C together. An entrance fitting 36 is provided at the lowermosttubular loop member of onei .15 outside group C, and an outlet fitting37 at the uppermost tubular loop member of the other outside group A sothat circulation of oil to be treated will take place from the bottom ofone group C to the top thereof, thence from .1 the top of group B to thebottom thereof, and from the bottom of the group A to the top, duringwhich circulation the exchange of heat between the heat transfer mediumand the oil will take place.

The heat transferring medium contemplated for use in this exchanger ismercuryvapor, and to that end there has been provided a distributingsystem of piping comprised of a feeder pipe 38 with branches 39 andlead- 7 each row of tubular members, and while only ers 40 connectedinto and distributing mercury vapor to the annular enveloping passages 6formed by the tubes 2 and 5 of the tubular loop members lying one withinthe other, while the liquid mercury is collected at the bottoms of theenlarged center portion of the return bends formed by the welded halves7 and 8 and drained away through connections 41 to the return pipe 42 ofthe mercury system, the condensed mercury being vaporized and againcirculated in vapor form.

In this manner it will be observed that there has been provided, whenthe exchanger is in operation, an enveloping jacket of heat transferringmercury vapor co-extensive with and surrounding each inner tube 2thereby providing as close thermal relation between the heattransferring mercury and the recipient oil to be treated as it ispossible to obtain without actual intermingling of the two fluids.

The enclosing casing of the bank of tubular loop heat exchangers may beof any simple form, but in the present instance it has been shown as ofbox-like construction, the bottom having a cross member 43 upon whichrests a channel member 44 in which the downwardly projecting lugs- 33 ofthe lowermost return bend fittings are seated.

The walls of the enclosing casing are of fiat plates 45 and 46 formingthe ends, each provided with angle members 47 adapted to be placed inabutting relation with'the loops of channel members 48 and 49' whichserve to hold the top plates 50 and side plates 51 in position.Intermediate thev length of the exchanger is a support for the returnbend end of the tubular loop members, this support comprising a pair ofupright channel members 52 on opposite sides of the heat exchanger andwhich serves to support their adjacent side plates 51, but through theweb is cold whereby clearance is provided for relative expansion of thetubes without strain on the welded terminal unctions of the tubes.

2. The method of assembling a heat exchanger unit which comprisesforming a return bendtube for the heat recipient fluid, slipping alarger tube over each leg of said bend, welding the terminal ends of thelarger tubes to those of the smaller tubes with the tubes held inconcentric relation to form a coextensive heat transfer jacket aroundthe inner tube, and welding together two halves of a return bend overthe inner tube to enclose the same and to the ends of the outer tube tocomplete the jacket, the said outer tube return bend having anincreasing cross sectional diameter from each extremity toward thecenter thereof to provide clearance for relative movement of the twotubes when heated.

WILLIAM A. JONES. JOHN PRENTICE.

of which is passed spacing rods 53, one for one supporting structure ishere shown'it is of course obvious that more may be required dependentupon the length of the tubular loop members.

Any of the usual forms of insulation against heat loss may be providedon the casing, such for instance as asbestos, magnesia or rock wool.

What I claim is 1.-The method of assembling a heat exchanger unit whichcomprises forming a return bend tube for the heat recipient fluid,slipping a larger tube over each leg of the said bend whereby a passageis formed around the first named tube for the heat transfer fluid,welding the tubes in concentric relation at the terminal ends, andforming a return bend connection enclosing the bend of the first tubeand connecting the remaining extremities of the larger tubes and withthe inner tube lying adjacent the extreme wall of the outer tubereturn'bend when the unit

